Acoustic topological insulator and robust one-way sound transport

TL;DR

This paper demonstrates a two-dimensional acoustic topological insulator that exhibits quantum spin Hall-like effects, enabling robust one-way sound transport immune to defects, with potential applications in acoustic device design.

Contribution

It introduces the first experimental realization of acoustic topological insulators with spin-dependent edge states based on band inversion near double Dirac cones.

Findings

Observation of spin-dependent one-way edge states

Topological immunity against defects and disorders

Potential for novel acoustic device applications

Abstract

Discovery of novel topological orders of condensed matters is of a significant interest in both fundamental and applied physics due to the associated quantum conductance behaviors and unique symmetry-protected backscattering-immune propagation against defects, which inspired similar fantastic effects in classical waves system, leading to the revolution of the manipulation of wave propagation. To date, however, only few theoretical models were proposed to realize acoustic topological states. Here, we theoretically and experimentally demonstrate a two dimensional acoustic topological insulators with acoustic analogue of quantum spin Hall Effect. Due to the band inversion mechanism near the double Dirac cones, acoustic one-way pseudospin dependent propagating edge states, corresponding to spin-plus and spin-minus, can be observed at the interface between two graphene-like acoustic crystals. We have also experimentally verified the associated topological immunity of such one-way edge states against the different lattice defects and disorders, which can always lead to inherent propagation loss and noise. We show that this unique acoustic topological phenomenon can offer a new promising application platform for the design of novel acoustic devices, such as one-way sound isolators, acoustic mode switchers, splitters, filters etc.